The proposed research will deal with the role of metallothionein in cadmium metablism as well as toxicity. A radioimmunoassay procedure will be developed to measure metallothionein. Using this procedure, plasma and urine samples from animals experimentally exposed to cadmium and from occupationally exposed humans will be assayed for metallothionein and its level will be correlated with renal tubular dysfunction. The human samples will be made available through collaboration with other investigators. Genetic predisposition for sensitivity to cadmium-induced testicular damage and hypertension has been suggested. This will be evaluated with respect to metallothionein levels in tissues. Inbred strains of mice will be used to study the relationship of metallothionein and testicular damage. Tissues from rats made hypertensive in response to chronic cadmium feeding will be obtained through a collaborative arrangement with another laboratory.